linux-kernel - Re: [PATCH] kasan, slub: fix more conflicts with CONFIG_SLAB_FREELIST

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Date:   Wed, 13 Feb 2019 20:56:25 -0500
From:   Qian Cai <cai@....pw>
To:     Andrey Konovalov <andreyknvl@...gle.com>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Alexander Potapenko <glider@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Christoph Lameter <cl@...ux.com>,
        Pekka Enberg <penberg@...nel.org>,
        David Rientjes <rientjes@...gle.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        kasan-dev <kasan-dev@...glegroups.com>,
        Linux Memory Management List <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>
Cc:     Vincenzo Frascino <vincenzo.frascino@....com>,
        Kostya Serebryany <kcc@...gle.com>,
        Evgeniy Stepanov <eugenis@...gle.com>
Subject: Re: [PATCH] kasan, slub: fix more conflicts with
 CONFIG_SLAB_FREELIST_HARDENED



On 2/13/19 7:27 PM, Andrey Konovalov wrote:
> On Thu, Feb 14, 2019 at 1:25 AM Andrey Konovalov <andreyknvl@...gle.com> wrote:
>>
>> When CONFIG_KASAN_SW_TAGS is enabled, ptr_addr might be tagged.
>> Normally, this doesn't cause any issues, as both set_freepointer()
>> and get_freepointer() are called with a pointer with the same tag.
>> However, there are some issues with CONFIG_SLUB_DEBUG code. For
>> example, when __free_slub() iterates over objects in a cache, it
>> passes untagged pointers to check_object(). check_object() in turns
>> calls get_freepointer() with an untagged pointer, which causes the
>> freepointer to be restored incorrectly.
>>
>> Add kasan_reset_tag to freelist_ptr(). Also add a detailed comment.
>>
>> Signed-off-by: Andrey Konovalov <andreyknvl@...gle.com>
> 
> Reported-by: Qian Cai <cai@....pw>

Tested-by: Qian Cai <cai@....pw>